1. Field of the Invention
The present invention relates to an improved novel inorganic silicon nitride continuous fiber composed of Si and N, and a method of producing the same.
2. Related Art Statement
Silicon nitride, which is a Si-N series inorganic compound, has been synthesized by various method from long ago. Among the various methods, high purity silicon nitrides can be obtained by a vapor phase reaction, a flux method, or a thermal decomposition of silicon diimide, as disclosed by Kijima et al in J. Am. Cer. Soc., Vol.56, p.340 (1973), Kijima et al in J. Cryst. Growth, Vol.24/25, p.183 (1974), Inomata et al in J. Cryst. Growth, Vol.21, p.318 (1974), and Mitomo et al in Journal of The Ceramic Society of Japan, Vol.82, p.144 (1974).
However, silicon nitride has been obtained in the form of powder or whisker solely, and not in the form of a continuous fiber. A continuous inorganic fiber containing the component N is produced by firing a polycarbosilane fiber in an inert atmosphere, as described in West German Patent No. 2218960 Specification. However, in this case, a fiber composed solely of Si and N is not obtained, and a fiber containing a large amount of C intermingled therein is obtained, which large amount of C causes a phase separation, various reactions, etc. at high temperature to deteriorate the characteristic properties of the fiber.